1. Field of the Invention
The invention relates to a wireless communication technology, and more particularly to a communication method for a mesh and star topology structure wireless sensor network featuring a hybrid multiple access and adaptive frequency hopping.
2. Description of the Related Art
Industries have benefited significantly from using wireless sensor networks (WSNs). In contrast with wired networks, wireless networks do not require wiring between nodes, and they are easy to maintain, highly flexible, and may be rapidly implemented, all of which exhibits obvious advantages in industrial applications. Wireless industry has developed as wireless communication technologies have matured and costs decreased. A typical industrial wireless measurement and control network is illustrated in FIG. 1. Nodes of wireless sensors or actuators are distributed at each observation point in an industry field. These nodes, together with those having a routing function, form a network, and send field monitoring data to gateway nodes via multi-hop routing. Aside from the convenience introduced by industrial wireless networks, the requirements for wireless networks imposed by industrial applications are strict and demand reliable, real-time operation with energy conservation to achieve high-quality communication. In terms of reliability, multi-frequency narrow band jamming, interference from coexisting networks, and multi-path effects are problematic for the use of scarce channel resource to achieve reliable communication. There is a need to identify solutions to the reliability problems associated with these effects. In terms of timeliness, industrial applications have more strict requirements than other applications because time is of the essence in industrial communications, and even a small delay can result in grave accidents. In terms of energy conservation, low energy consumption is a key to guaranteeing long-term operation, as well as to reducing costs, especially for nodes attached to power sources that are difficult to replace. Because the WSN technology is feasible in practice, more and more people are recognizing the advantages of a carefully crafted communication topology, particularly the communication process used in mesh and star topology WSNs (MSTN). MSTNs are typical of WSNs used in industrial applications. However, an MSTN that can simultaneously realize reliable, real-time, and energy-saving communication has not been reported.